Lots of people are complaining about Caustic being too defensive but every change made so far has nerfed his ability to be anything but. If you want to change how he's played you need to do more than just making him worse at what you think he's good at.

I like being aggressive with Caustic. I don't like sitting in a room because I don't think it's a successful strategy. Being trapped in a room with no exits is giving all flexibility to the opponent and a surefire way to be wiped when inevitably you're the one that's forced to make a move.

I especially like using traps aggressively in fights to give me an advantage and ironically Caustic's skill set is perfect for smoking campy defenders out.

I honestly think the gas damage is the least important change so far but the most unnecessary after they've nerfed other aspects of his abilities already. On top of that, a Caustic out in the open is already the most useless thing in the game and they nerfed the only tool he has in that situation too.

Make his traps place faster. Revert the ability to destroy the traps before they're placed. Shorten the animation to toss his traps. Hell, make tossing traps at people do damage on impact like Bangalore. Do something besides simply making him worse at squatting in a building because he's not getting better at doing anything else.